linux-kernel - [PATCH 1/3] signal: Ensure SIGNAL_GROUP_EXIT gets set in do_group

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Date:   Wed, 22 Jun 2022 11:45:20 -0500
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, mingo@...nel.org,
        bigeasy@...utronix.de, Peter Zijlstra <peterz@...radead.org>,
        Jann Horn <jannh@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Robert O'Callahan <roc@...nos.co>, Kyle Huey <khuey@...nos.co>,
        Keno Fischer <keno@...iacomputing.com>
Subject: [PATCH 1/3] signal: Ensure SIGNAL_GROUP_EXIT gets set in do_group_exit

The function do_group_exit has an optimization that avoids taking
siglock and doing the work to find other threads in the signal group
and shutting them down.

It is very desirable for SIGNAL_GROUP_EXIT to always been set whenever
it is decided for the process to exit.  That ensures only a single
place needs to be tested, and a single bit of state needs to be looked
at.  This makes the optimization in do_group_exit counter productive.

Make the code and maintenance simpler by removing this unnecessary
option.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 kernel/exit.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index f072959fcab7..96e4b12edea8 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -905,7 +905,7 @@ do_group_exit(int exit_code)
 		exit_code = sig->group_exit_code;
 	else if (sig->group_exec_task)
 		exit_code = 0;
-	else if (!thread_group_empty(current)) {
+	else {
 		struct sighand_struct *const sighand = current->sighand;

 		spin_lock_irq(&sighand->siglock);
-- 
2.35.3